1. Field of the Invention
The present invention relates to a flat display, and more particularly, to a sealing area of a flat display in which an acryl-type moisture-resistant coating layer is formed on the surface of a frit glass exposed to the air.
2. Description of the Related Art
Generally, flat displays include plasma display panels (PDPs), liquid crystal displays (LCDs), vacuum fluorescent displays (VFD), electroluminescent (EL) displays and field emission displays (FEDs). In PDPs, a gas is injected into cells formed between two substrates having transparent electrodes of a predetermined pattern before sealing the cells, a discharge voltage is applied to the sealed cells, and ultraviolet rays generated due to the discharge voltage excite phosphors formed in a predetermined pattern, thereby displaying desired numerals, characters or graphics.
As shown in FIG. 1, a PDP includes a front substrate 11 and a rear substrate 12. Common electrodes 13 and scanning electrodes 14 are formed on the bottom surface of the front substrate 11 in a stripe pattern. Bus electrodes 15 are formed on the common and scanning electrodes 13 and 14 to reduce line resistance. A dielectric layer 16 is formed on the bottom surface of the front substrate 11 such that the common and scanning electrodes 13 and 14 are embedded in the dielectric layer 16. A protective layer 17, for example, a MgO layer, is formed on the dielectric layer 16.
Meanwhile, address electrodes 18 are formed on the rear substrate 12 to be opposed to the front substrate 11 in a strip pattern crossing the common and scanning electrodes 13 and 14. The address electrodes 18 are embedded in a dielectric layer 19. Partition walls 100 for defining discharge spaces are formed on the dielectric layer 19. Each cell defined by the partition walls 100 is coated with a phosphor material layer 110 of red, green and blue (RGB).
In the operation of the conventional PDP having the above structure, once a voltage is applied between the scanning electrodes 14 and the address electrodes 18, pre-discharge occurs and wall charges are produced in the discharge space. In the discharge spacing having the wall charges, main discharge occurs between the common electrodes 13 and the scanning electrodes 14, thereby forming plasma. Ultraviolet rays are emitted from the plasma and excite the phosphor material layers 110, thereby realizing an image.
To fill the inside of the PDP with a discharge gas, a panel comprised of the front and rear substrates 11 and 12 are sealed using frit glass to hold the airtightness of the space between the front substrate 11 and the rear substrate 12, and the space is vacuum evacuated and filled with a gas. For this purpose, as shown in FIG. 2, an evacuation hole 21 is formed on the rear substrate 12, and an evacuation pipe 22 is provided around the evacuation hole 21. The evacuation pipe 22 is sealed to the rear substrate 12 through a sealing area 23 composed of a frit glass 23a. In other words, the frit glass 23a is melt at a predetermined temperature, thereby sealing the evacuation pipe 22.
However, because the sealing area is exposed to the air, the surface of the sealing area tends to deform to an acicular shape due to permeation of moisture under a hot and humid environment. The surface of the sealing area is visually shiny and smooth in a normal state. In an experiment for testing an environmental reliability, moisture gradually made its way under the surface of the frit glass 23a in a test environment of 50xc2x0 C. and 98% humidity and finally the surface of the sealing area deformed as if salt was sprayed on the surface thereof. Flat display products are sold in many regions in various climates. In this case, when products are exposed to an hot and humid environment for a long period of time, a sealing area deforms resulting in cracks on the surface of the sealing area or vacuum break of a panel.
To solve the above problem, an object of the present invention is to provide a sealing area of a flat display in which an acryl-type moisture-resistant coating layer is formed on the surface of a frit glass exposed to the air.
To achieve the above object, the present invention provides a sealing area of a flat display. The sealing area includes front and rear substrates provided to be opposed to each other, which are sealed to each other using frit glass so as to form a discharge space, an evacuation pipe sealed to the outer surface of the rear substrate using frit glass, and a moisture-resistant coating layer formed on the surface of the frit glass.
The moisture-resistant coating layer is preferably formed on the surface of the frit glass and the surface of the evacuation pipe.
The moisture-resistant coating layer is formed of an acryl-type material preferably including 28.6% of acryl resin, 9.9% of aromatic solvent, 8.3% of alcohol solvent and 8.3% of ester solvent.
The moisture-resistant coating layer is preferably 10 nm thick.